Preparation of phenol sulfides



UNITED STATES PREPARATION OF PHENOL SULFIDES Louis A. Mikeska,Wcstfield, and Eugene Lieber,

Linden, N. J., assignors to Standard Oil D evelopment Company, a.corporation of Delaware No Drawing. Application August 21, 1936, SerialNo. 97,196

19 Claims.

This application relates to an improved process for the preparation ofphenol sulfides. It relates more particularly to the preparation of suchsulfides by reaction of phenols with sulfur chlorides in an inertsolvent with the simultaneous evolution and removal of hydrogen chlorideunder conditions adapted to favor the formation of improved yields ofphenol sulfides of high purity and to avoid the formation of highmolecular Weight insoluble or resinous products.

It is already known that phenol and sulfur dichloride may be condensedin the presence of carbon disulfide. Such reaction is conducted at a lowtemperature. The yield of phenol sulfide is low and the product isobtained in such an impure form that it requires extensive purification.It has now been found that if the reaction of phenol, particularly alkylphenols, and sulfur chloride is conducted in suitable solvents attemperatures of about 60 to 140 C. and preferably at a temperature ofabout 80 to 110 C. yield of desired products is greatly increased andthe products are of such high purity that crystalline products can beobtained merely by distillation of the crude reaction mixture. Thefollowing examples are presented to illustrate preferred modificationsof this invention and are not intended to limit it in any way.

Example 1 (CICI-IzCHzCl) and the solution was heated to boiling underreflux. grams (0.52 molal proportion) of sulfur dichloride (SClz) weredissolved in 100 cc. of ethylene chloride. This solution was added 40slowly, with stirring, to the boiling solution of amyl phenol. Thehydrogen chloride gas evolved during the reaction was withdrawn from thereaction zone through the reflux condenser. When the addition of thesulfur dichloride solution was completed, the boiling of the reactionmixture under reflux was continued for six hours until no furtheremission of hydrogen chloride was detectable. By this means, allhydrogen chloride is removed and there is no need to wash the reactionproduct with water. The time of refluxing can be cut down by blowing aninert gas such as nitrogen or flue gas through the reaction mixture.This may be done during the reaction or after all the reagents have beenadded, as desired.

The solvent, ethylene chloride, was then removed from the reactionmixture by distillation and the resulting product was distilled under avacuum of 3 mm. mercury absolute pressure. .There were thus obtained (1)a fraction distilled below 230 (3., consisting of 20 gms. of unreactedphenol, (2) a fraction distilled between 230 and 235 C'., and consistingof 108 gms. of amyl phenol sulfide, and (3) 10 gms. of residue.

The yield of amyl phenol sulfide recovered as distillate was 92.1%,based on the amount of amyl phenol reacting. It is a clear bright yellowliquid which on standing or being seeded crystallizes to a light yellowsolid. Both the liq uid and solid forms are soluble in ether, alcohol,acetone, carbon disulfide, liquid hydrocarbons, hydrocarbon halides,petroleum oils and fractions thereof, including gasoline, kerosene,burning and Diesel oils and lubricating oils, and in most organicsolvents.

The residue was easily removable from the distilling flask with ordinaryorganic solvents such as ether or chloroform. There was no cokeformation.

The reaction is preferably conducted under anhydrous conditions. Toinsure this the first reflux condensate may be withdrawn until thestream is clear, when it is returned to the reaction zone. Instead ofadding the sulfur chloride in solution in the solvent, the entire volumeof solvent may be added initially or as desired, and the sulfur chloridemay be added slowly to the reflux stream.

The equipment in which the reaction is conducted should be non-corrosiveby the materials used and the reaction products. It is preferably madeof or lined with glass or other acid and sulfur resistant ceramicmaterial or metal, such as pure nickel and suitable alloys.

When the above process is conducted. with 40 carbon disulfide as thesolvent during the reaction, the yield is less than 50% and the productis very impure and non-crystalline. Much coke is formed when itsdistillation is attempted.

The above example illustrates the preparation of an alkyl phenolsulfide, using sulfur dichloride as the reagent. Polymers of the alkylphenol sulfide may be obtained by using a slightly larger ratio ofsulfur dichloride to alkyl phenol, prefr erably a ratio in theapproximate range from 0.6 to 0.75. In this manner, there is. obtainedas the reaction product a mixture of alkyl phenol sulfide and ofpolymers thereof, of which the polymers may amount to from 10 to 30% ofthe 55 mixture. For example, when using a ratio of 0.4 mol of sulfurdichloride to 1 mol of alkyl phenol, the resulting product consistssubstantially entirely of alkyl phenol sulfide. When using a ratio of0.5, the resulting product contains about alkyl phenol sulfide and about10% of a polymer thereof. When using a ratio of 0.75, the productcontains about 70% of alkyl phenol sulfide and about 30% of polymersthereof. When using larger proportions, products are formed which arenot soluble in petroleum lubricating oils. The polymers, as illustratedin Example 1, may be separated from the reaction mixture by distilling01f the alkyl phenol sulfide under vacuum. Their formation is furtherillustrated in the following examples:

Example 2 The same procedure for conducting the reaction was used as inExample 1, except that 50 gms. of sulfur dichloride was used (0.65 molalratio of sulfur dichloride to phenol). After removal of the solvent, thereaction mixture was distilled under vacuum to a temperature of 210 C.at an absolute pressure of 3 mm. mercury and there were obtained, as thedistillation residue, 131 gms. of amyl phenol sulfides, representing ayield of 95.9% based on the amyl phenol reacted. This product was darkbrown to red in color, and crystallize-d slowly on standing. Itcontained about 15% of non-distillable polymers of amyl phenol sulfide.These polymers are also soluble in the same solvents described inExample 1 as solvents for the amyl phenol sulfide.

The polymers may also be formed by bringing a phenol sulfide intoreaction with additional sulfur halide. This is a preferred procedure.when large yields of the polymer are desired. A suitable method ofpreparing the polymers is according to the process described in Example1 The amount of sulfur dichloride used is preferably about half theamount (molal basis) of the phenol sulfide.

Example 3 Two mols of distilled tertiary amyl phenol sulfide,substantially free of unreacted phenols and of polymers, was broughtinto reaction with one mol of sulfur dichloride in ethylene chloride,boiling under reflux, according to the procedure described in Example 1.After distilling off the solvent from the reaction mixture, this washeated under a vacuum of 3 mm. mercury absolute pressure. No distillatewas obtained to 250 0., indicating a theoretical yield of the polymer.This product is a dark red viscous liquid and is readily soluble in thematerials listed as solvents for the alkyl phenol sulfide product inExample 1.

Instead of the sulfur dichloride reagent, sulfur monochloride (S2012)may be substituted in the processes described in Examples 1 and 2-forthe production of phenol disulfides and polymers thereof. It may also besubstituted for sulfur dichloride in the process described in Example 3to produce polymers of phenol sulfides in which the original moleculesare joined together by a disulfide linkage. Other combinations of thesetwo sulfur halide reagents may be used. For example, phenol disulfidesmay be brought into reaction with sulfur dichloride with the formationof polymers in which the original phenol disulfide molecules are linkedby a single atom of sulfur. The preferred proportions of sulfurmonochloride are the same as those indicated for use with sulfurdichloride.

Example 4 Qne mol of butyl phenol is brought into reaction with mol ofsulfur monochloride under the same conditions described in Example 1.The solvent and any unreacted butyl phenol are removed by distillation.The residual product is largely butyl phenol disulfide, with a smallamount of polymers. It is not distillable. It is soluble in the samesolvents described as solvents for the product of Example 1, includingpetroleum oil and fractions thereof from gasolines to lubricating oils.

A convenient method for handling the reaction products, especially whenthe alkyl phenol sulfides are to be used in blends with mineral oils, isto add a petroleum lubricating oil during or after the removal ofsolvent by distillation at atmospheric pressure. Any amount of oil maybe used, to 2 volumes of oil per volume of the alkyl phenol sulfidebeing usually satisfactory. Any remaining solvent and unreacted phenolsare then easily removed by distillation without danger of overheatingthe desired product. The last traces of solvent may be removed byheating the oil to about C. under a vacuum below 100 mm. mercury, andpreferably below 20 to 10 mm. The last traces of hydrogen sulfide mayalso be removed from the reaction product by blowing it with an inertgas, either during or after the above described distillations. Air maybe used, preferably at atmospheric temperature, although temperatures upto about 100 C. or higher may be used.

The present invention may be used to prepare phenol sulfides from phenoland both cyclic and aliphatic derivatives thereof such as naphthols,cresols and higher alkylated derivatives containing one or more alkylgroups of two or more carbon atoms each attached to the aromaticnucleus. Other derivatives of phenols may be used in which othersubstituent groups may be attached to the aromatic nucleus in additionto or in substitution for the alkyl and aryl groups, provided only thatthe additional substituent groups do not greatly alter the nature of thereaction. The invention is particularly suited to the preparation ofalkyl phenol sulfides from alkyl phenols containing alkyl groups ofabout 2 to 8 carbon atoms such as butyl phenols, amyl phenols, hexylphenols and the like and from mixtures of such phe-- nols. Suitablebranched alkyl phenols, i. e., in which the carbon atom of the alkylgroup connected to the benzene ring is also connected to at least twoother carbon atoms of the alkyl group, can be prepared by condensingphenols with olefins of about 3 to 8 or more carbon atoms per molecule,or with mixtures of olefins, such as those obtained by the cracking ordehydrogenation of hydrocarbons, petroleum oils, etc. Ortho and parasecondary and tertiary butyl and amyl phenols are preferred initialreagents. These may be used separately or in any desired mixture. Theinvention is also applicable to the preparation of phenol sulfides frompolyhydroxy aromatics such as resorcinol, hydroquinone and theiralkylated derivatives.

The reaction is preferably conducted at a temperature of 80 to C. Theproducts obtained in this range of temperatures are of excellent color,and, excepting the polymers and disulfides, are distillable and can beobtained in crystalline form merely on distillation of the crudemixture. When using reaction temperatures below about 60 C. or aboveabout C., the products are 75 obtained in a much lower yield, have apoor color, and cannot be obtained in crystalline form. The samedisadvantages apply when using other solvents than the organic halidesdescribed, for example, when using carbon disulfide or naphtha.

The crude products may also, if desired, be subjected to furtherpurification in addition to, or in combination with or in place of thedistillations described above. Preparation of products of enhancedpurity may be accomplished by fractional crystallization, by extractionor precipitation with selective solvents. Impurities may also be removedby treatment with suitable adsorptive agents, such as clay.

Solvents suitable for use in this invention are the organic halideswhich are inert or react only very slowly with the reagents used andwhich preferably have a boiling point within the range of temperaturesindicated to be suitable for the reaction. Among such solvents may bementioned, for example, ethylene chloride, carbon tetrachloride,chloroform, tetrachlorethane, both symmetrical and unsymmetrical,trichloroethane, trimethylene dichloride, dichlorpropane, propylenechloride, propylidene dichloride, acetone chloride, trichloro propane,dichloro pentane, phenyl chloride and the corresponding derivatives ofthe other halides, such as the bromides and iodides, which boil withinthe same range. The saturated alkyl halides, boiling between about and110 C., are the preferred solvents, although those boiling as low as 60C. and as high as 140 C. may be used, as even their use permitssubstantial advantages over solvents boiling outside this range.Solvents of higher or lower boiling points may also be used if thereaction is conducted under suitably reduced or elevated pressure tocause the solvent to boil in the desired range, although this procedureinvolves difficulties in the removal of the hydrogen halide formedduring the reaction and is accordingly not commonly used. The amount ofsolvent may vary over a wide range, and is preferably at least equal involume to the alkyl phenol. Larger amounts, from two to five or tenvolumes, are generally used.

The sulfur chloride or other sulfur halide used is preferably of highpurity, although commercially pure grades containing a few percent offree sulfur may be used. Either sulfur chloride or sulfur dichloride maybe used, depending on whether a phenol sulfide or disulfide is desiredas the product. Mixtures of the two sulfur chlorides may also be usedwith either present in any proportion from 0 to there being thusobtained a corresponding mixture of a phenol sulfide and a phenoldisulfide. A preferred mixture of sulfur chlorides contains from 10 to35% of sulfur dichloride, the remainder being sulfur monochloride. Itmay be used in the same manner as the separate sulfur chloridesdescribed in the above examples. The products, which are preferablyobtained as a vacuum distillation residue, as in Example 2, areespecially effective as oxidation and corrosion inhibitors.

The process of this invention is also suitable for the preparation ofalkyl phenol derivatives of the other non-metallic elements of group 6of the periodic system of higher atomic weight than sulfur bysubstitution of suitable halide reagents thereof for the sulfurchlorides in the reactions described above. For example, alkyl phenolselenides may be prepared under the same conditions described above bysubstituting selenium oxychloride (Se0C12) in place of sulfur chlorideor dichloride.

This invention is not to be limited to any theoretical explanations ofthe reactions described or to any of the specific: examples presentedherein, all of which have been presented solely for purpose ofillustration, but is limited only by the following claims, in which itis desired to claim all novelty insofar as the prior art permits.

We claim:

1. Improved process for preparing hydroxy aromatic sulfides comprisingbringing a phenol free from 'carboxyl groups and a halide of anonmetallic element of Group VI into reaction at a temperature between60 and 140 C. in an inert solvent boiling at the reaction temperatureunder reflux while removing the hydrogen halide formed.

2. Process according to claim 1, in which said reaction temperature isbetween 80 and C.

3. Improved process for preparing hydroxy aromatic sulfides comprisingbringing a phenol and a halide of, a non-metallic element of Group VI,the ratio of the halide to the phenol being between the limits of 0.3and 1.0, into reaction at a temperature between 60 and C., in an inertsolvent boiling at the reaction temperature under reflux while removingthe hydrogen halide formed.

4. Process according to claim 1, in which said solvent is an organichalide.

5. Improved process for preparing hydroxy aromatic sulfides comprisingbringing a phenol and a halide of a nonmetallic element of Group VI intoreaction at a temperature between 60 and 140 C. in a saturated aliphatichalide solvent boiling between about 60 and 140 C., said solvent boilingat the reaction temperature under reflux while removing the hydrogenhalide formed.

6. Process according to claim 1, in which said phenol is an alkyl phenolhaving an alkyl group of two or more carbon atoms.

7. Process according to claim 1, in which said phenol is an alkyl phenolhaving an alkyl group of four to six carbon atoms.

8. Process for preparing an alkyl phenol sulfide of the typeR(C6H4)OH.S(C6H4)OH.R', in which R and R are alkyl groups of two or morecarbon atoms comprising bringing the corresponding alkyl phenol andsulfur dichloride into reaction at a temperature of 60 to 140 C. in aninert organic halide solvent boiling at the reaction temperature underreflux While removing the hydrogen chloride formed during the reaction.

9. Process according to claim 8, in which the reaction is conducted witha ratio of sulfur dichloride to alkyl phenol within the limits of about0.3 and 1.0.

10. Process according to claim 8, in which the said solvent is ethylenechloride.

11. Process for the production of polymers of alkyl phenol sulfidesaccording to claim 8, in which the reaction is conducted with a ratio ofsulfur dichloride to phenol within the limits of about 0.6 and 0.8, andthe polymers are obtained as a residue on distilling the alkyl phenolsulfide.

12. Process for the preparation of polymers of alkyl phenol sulfidescomprising bringing an alkyl phenol sulfide and a sulfur chloride intoreaction at a temperature of 60 to 140 C. in a saturated alkyl halidesolvent boiling at the reaction temperature under reflux and removingthe hydrogen chloride formed during the reaction.

13. Process for preparing alkyl phenol disulfides of the type R(CsI-I4)OH.S2(C6H4)OH.R', in which R and R are alkyl groups of two or morecarbon atoms comprising bringing the corresponding alkyl phenols intoreaction with sulfur monochloride at a temperature of 60 to 140 C. in aninert organic halide solvent boiling at the reaction temperature underreflux while removing the hydrogen chloride formed during the reaction.

14. Process according to claim 13, in which the molal ratio of sulfurmonochloride to alkyl phenol is between the limits of 0.3 and 1.0.

15. Process for preparing tertiary amyl phenol sulfide comprisingdissolving substantially 2 mols of tertiary amyl phenol and 1 mol ofsulfur dichloride in separate portions of ethylene chloride, slowlybringing the solutions into contact while boiling the ethylene chlorideunder reflux and removing the hydrogen chloride, continuing therefluxing until no further liberation of hydrogen chloride is apparentand separating the resulting tertiary amyl phenol sulfide from thereaction mixture.

16. Process for preparing tertiary amyl phenol disulfide comprisingdissolving substantially 2 mols of tertiary amyl phenol and 1 mol ofsulfur monochloride in separate portions of ethylene chloride, slowlybringing the solutions into contact while boiling the ethylene chlorideunder reflux and removing hydrogen chloride, continuing the refluxinguntil no further liberation of hydrogen chloride is apparent andseparating the resulting tertiary amyl phenol disulfide from thereaction mixture.

17. Improved process for preparing hydroxy aromatic sulfides, comprisingbringing a phenol free of carboxyl groups and a chloride of sulfur intoreaction at a temperature between 60 and 140 C. in an inert solventboiling at the reaction temperature under reflux, and removing thehydrogen chloride formed.

18. Process for preparing an'alkyl phenol sulfide, comprising bringingan alkyl phenol free of carboxyl groups and a sulfur chloride intoreaction with a ratio of sulfur chloride to alkyl phenol within thelimits of 0.3 and 1.0, at a temperature of 60 to 140 C. in an inertorganic halide solvent boiling at the reaction temperature under refluxwhile removing the hydrogen chloride formed during the reaction. A

19. Process for preparing an alkyl phenol sulfide comprising bringing analkyl phenol free of carboxyl groups and a sulfur chloride, with a ratioof sulfur chloride to alkyl phenol within the limits of 0.3 and 1.0,into reaction at a temperature between 60 and 140 C. in a saturated,alkyl chloride solvent while removing the hydrogen chloride formed.

LOUIS A. MIKESKA.

EUGENE LIEBER.

